Protect

PORCUPINE

Cache County

Fathom Restoration

41° 31′ 08″ N

111° 44′ 12″ WPORCUPINE RESERVOIR

A hundred and ninety acres of privately owned irrigation water with a wild salmon run in it, no boat ramp, no toilets and a private fence sixty seven metres from the inlet. Every figure is quoted from an agency, and where agencies disagree all of them are printed.

190Acres, or 179 in the same record

0Kokanee stocked since 2021

181 ftDam height

1962Dam completed

1Listed purpose: irrigation

Conditions right now

Both federal gauges on the East Fork Little Bear River are discontinued, one since 1986 and one since 1951, so there is no live flow measurement for this reservoir. What is below is the forecast, a monthly federal storage figure, and the nearest gauge that still reports, which is on a different river.

Forecast at the reservoirNWS

–

contacting the National Weather Service

Stored, monthlyNRCS

–

reading the federal reservoir record

Nearest gauge still reportingUSGS

–

Little Bear River at Paradise, a different river seven miles away

The gauges that diedUSGS

1986 & 1951

Two gauges were run on the East Fork Little Bear, above the reservoir and below the dam. Neither has reported in decades, and nothing replaced them.

About · 01

What Porcupine is

A small private farm reservoir that happens to grow its own salmon, which is why anyone drives up there at all.

Porcupine is small. The federal hydrography polygon measures 179 acres ; Utah's water quality record for the same reservoir carries 190 in one field and 179 in the next . Either way it would fit inside Utah Lake five hundred times over.

It is a farm reservoir. The federal dam register lists the owner as Porcupine Reservoir Company, owner type Private, and the purpose as one word: Irrigation . Utah's dam safety record names the same dam and rates it the same way .

And yet the kokanee here are wild NONE STOCKED

Utah's stocking record for this water goes back through 2021 and contains no kokanee at all . Rainbows go in every May, splake and lake trout most summers, tiger trout once in 2021. Kokanee, never.

They spawn up the East Fork Little Bear River on their own, which is why there is a closure on that river and not on most others . This is the rare Utah water where the headline fish is not put there by a truck.

There is no boat ramp. Utah publishes a statewide boat ramp inventory of 117 ramps across 57 waters, and Porcupine is not in it . There is no state park, no Forest Service site, and no published fee. Boats are allowed but "Operating a boat above wakeless speed is prohibited."

This is what Porcupine is known for, and the wildlife agency publishes the whole thing plainly.

The agency describes the change itself: kokanee are a shade of silver for most of the year and turn bright red in September and October, before running up rivers and streams to spawn . "The males also acquire humped backs, hooked jaws and elongated teeth during their spawning transformation."

"Kokanee salmon run up the east fork of the Little Bear River, which is the main source of water for Porcupine Reservoir." "Peak spawning time is the middle of September."

Three things people get wrong DO NOT

"Visitors should also not disturb the spawning fish by wading into the water, allowing their dogs to chase the fish or by trying to pick the fish up."

And the one that carries a penalty: "You are not allowed to keep any kokanee salmon caught anywhere in Utah from Sept. 10 to Nov. 30, during the spawning season."

The run is not the same size every year, and the agency says why. A wildlife agency biologist, quoted in the local paper: "The kokanee population will build up every four to six years and then it will drop. It's kind of a self-regulating mechanism." Worth knowing before you drive an hour for it.

One honest caveat. The wildlife agency's published viewing guidance for Porcupine dates to its 2020 to 2022 releases . Its most recent kokanee viewing article, from 2025, lists six places to go and Porcupine is not among them . That may mean nothing, or it may mean they are steering crowds elsewhere. This page prints what they published rather than guessing which.

The wildlife agency is blunt about the parking: "Parking is very limited, though." "If you head to Porcupine Reservoir, please park in the small parking lot and avoid parking on the road, if possible." "Visiting on weekdays or timing your trips for early or late in the day may be your best option for finding parking."

Do not walk up the inlet PRIVATE LAND

The agency names it: "Do not trespass on Cinnamon Creek Campground's land, which is located just upstream, and is marked with a 'no trespassing' sign and locked gate."

Here is how little room there is. The reservoir's inlet is at the eastern tip of the water . The campground's western property line, mapped independently by Cache County's parcel layer and by OpenStreetMap and agreeing to within four metres, has its nearest mapped point 67 metres from that inlet . The public road ends at a gate 300 m west of the inlet, and Utah's own road dataset ends the county segment there too .

So the walkable public stretch of the spawning stream is very short. Every pin for this is on the map in the Recreation section, including the campground, so you can see exactly where the line is.

SR-165 does not go there ROUTE

A lot of write ups say to take Utah 165 south from Paradise to the reservoir. Utah's road dataset says State Route 165 ends in Paradise, about six kilometres from the mouth of the canyon . Everything after that is county road, and the pavement runs out 659 m short of the dam .

Figure	Value	Source
Owner	Porcupine Reservoir Company, private	National Inventory of Dams
Purpose	Irrigation, and only irrigation	National Inventory of Dams
Type	Earth	National Inventory of Dams
Structural height	181 ft	National Inventory of Dams
Crest length	665 ft	National Inventory of Dams
Year completed	1962	National Inventory of Dams
Maximum storage	15,000 acre-feet	National Inventory of Dams
Normal storage	13,000 acre-feet	National Inventory of Dams
Hazard classification	High	National Inventory of Dams , Utah Water Rights
Regulated by	Utah Division of Water Rights, not federal	National Inventory of Dams

A high hazard rating describes what is downstream if the dam fails, not the chance of it failing . The register lists the last inspection as 8 June 2023, and the emergency action plan as last revised in 2020 .

The condition assessment is 35 years old DATED 1991

The federal register records Condition Assessment: Satisfactory, and beside it Condition Assessment Date: 01/01/1991 . The dam has been inspected since, most recently in 2023, but the published condition rating is the one from 1991. That is what the register says, so that is what this page prints.

Height is measured two ways in the same record: 181 ft structural and NID height, 167 ft hydraulic . They measure different things. This page uses 181 and says which.

East Fork Little Bear River

In at the east end, and that inlet is the whole kokanee story . The gauge that measured it here stopped in 1986 .

Porcupine

Held behind 181 feet of earth finished in 1962, privately owned, for one listed purpose .

Out at the dam, for irrigation

Back into the East Fork, where the rules tighten to two fish, flies and lures only . The gauge below the dam stopped in 1951 .

Little Bear, Bear, Great Salt Lake

The main stem and the South Fork are both on the impaired list for temperature. Porcupine and its own two reaches are not .

The East Fork Little Bear River comes in at the east end and leaves at the dam, then joins the Little Bear, then the Bear River, which ends in the Great Salt Lake.

Below the dam the river gets its own rules: "Limit 2 trout or salmon (a combined total, regardless of species)." and "Artificial flies and lures only.", from the dam down to the second stream crossing on the Avon to Paradise road .

The gauges here are all dead. Two federal streamgauges were run on the East Fork, one above the reservoir and one below the dam. The one above stopped in 1986. The one below stopped in 1951 . Neither will ever report again, and the live card at the top of this page reads a gauge on the main stem at Paradise instead, which is a different river seven miles away. It says so on the card.

Science · 02

The numbers, and the water

Nobody publishes how deep it is, everybody publishes a different acreage, and for once the water itself comes back clean.

Figure	Value	Source
Surface area	190 acres, or 179 in the next field of the same record	Utah environmental quality
Surface area, measured	179.2 acres from the water body polygon	Federal hydrography
Surface area, as the wildlife agency lists it	190 surface acres	Utah wildlife agency
Elevation	5,380 ft	Federal soil conservation service
Maximum storage	15,000 acre-feet	National Inventory of Dams
Drainage area	72 square miles	National Inventory of Dams
County	Cache	Federal names database

Maximum depth: not published. No agency we could reach prints a maximum or mean depth for this reservoir. Utah's dam record leaves the crest elevation field blank. So this page does not put a depth on it, and it is the only lake page in this series without one.

Shoreline length: not published either. Same answer.

How good is the drawing on this page HONEST ANSWER

The shape is excellent and the area is not. Measured against the federal hydrography polygon's own bounding box, the outline is 2,208 units wide by 1,000 tall against a real 2,492 m by 1,128 m, so the proportions are right to within 0.1 per cent on both axes .

Scale it by that same extent and the area it encloses works out at about 208 acres, against the 179 the hydrography actually measures . The trace is roughly 16 per cent fatter than the water body, most of that in the long east arm, which a 73 point outline cannot hold at this size. Treat it as a silhouette of the right shape in the right place, and not as a measurement.

Like every irrigation reservoir in this series, Porcupine is spent through the summer. The federal soil conservation service publishes the monthly storage .

What is actually in it, month by month

20252026

Acre feet, monthly, from the federal soil conservation service's record for Porcupine Reservoir . The dashed line is the normal storage figure the federal dam register gives . 2026 runs to July, which is the latest month published.

It sat at 13,000 acre feet in March and April, which is exactly the normal storage figure the dam register gives , and it was down to 7,260 by the end of July . That is a loss of about 44 per cent of its contents across the irrigation season.

There is no agency sentence anywhere describing the Porcupine drawdown in words. The numbers above are the whole published record of it. Note also that Porcupine was not among the seven waters given emergency increased limits for low water in July 2026 .

This is the first reservoir in this series that comes back clean.

Assessment	2: Supports all assessed uses
Impairment	NA
TMDL required	none
TMDL approved	none

That is Utah's 2026 assessment record for Porcupine Reservoir, assessment unit UT-L-16010203-009_00 . Compare Yuba, which is on the impaired list for harmful algal blooms with no cleanup plan approved.

The river above and below is assessed the same way: the reach from the reservoir down to the Little Bear "Supports all designated uses", and Porcupine Creek "Supports all assessed uses" . Further downstream is a different story, where the Little Bear main stem and the South Fork are both on the impaired list for temperature . Precision matters here: the Little Bear is impaired, but not at Porcupine.

There is no mercury advisory at Porcupine A CLAIM WORTH KILLING

At least one fishing site publishes that Porcupine Reservoir is listed on Utah's fish advisory for mercury in brown trout. It is not. Utah's fish consumption advisory list names twelve waters and Porcupine is not among them .

The claim is not invented out of nothing, which is why it is worth being precise. Utah's mercury in fish tissue dataset does carry a Fish Consumption Advisory flag on brown trout sampled here in 2006 and 2007. The 2015 resample of the same site flips to No Advisories Issued, and kokanee and rainbow trout are clear in every year sampled . So: there was a flag, it was nearly twenty years ago, the next sample cleared it, and there is no current advisory. The most recent data is eleven years old.

Storage is monthly and it is real. The federal soil conservation service has published storage for this reservoir since 1965 . Its daily series is advertised and returns nothing, so the card above prints the month the figure belongs to.

The flow card is not this river. Both federal gauges on the East Fork Little Bear are discontinued: the one above the reservoir ended in 1986 , the one below the dam in 1951 . The nearest gauge still reporting is on the Little Bear River at Paradise , on the main stem about seven miles north west and below the confluence. It is a useful indication of what the whole drainage is doing and it is not the Porcupine outflow. The card says so.

This is the honest version of a common trick. It would be easy to put a gauge number on a page and let people assume it measures the water in front of them. On this reservoir nothing does.

Recreation · 03

Getting on the water

No ramp, one small lot, a gate, and a boundary you must not cross.

The whole reservoir

Area centroid of the USGS National Hydrography water body polygon, which on this reservoir falls on open water. The federal names point for Porcupine Reservoir, feature 1444586, sits within a metre of it.

Open in Google Maps →Directions →

Water body and inlet from the federal hydrography, the dam from the federal dam register, the private boundary from Cache County parcels, the road nodes from Utah's road dataset, the wildlife management area from the state wildlife agency, and the parking, gate and shore tracks from OpenStreetMap, which says so on every pin that uses it.

Leg	What it is
To Paradise	State Route 165 ends here. It does not continue to the reservoir
Paradise to the canyon	County road east, about six kilometres
Up East Canyon	Paved county road, until it is not
Pavement ends	659 m west of the dam. Everything east of that node is coded improved rather than paved in Utah's road data
Past the dam	Gravel along the north shore
Northeast parking	The small lot the wildlife agency points people to
The gate	300 m further east. Public road ends
Beyond	Private. Do not

Visitors describe the last stretch as narrow gravel with steep edges, and no toilets anywhere . Take that as the character of the place rather than a spec: it is a small reservoir on a farm road with a very good salmon run and almost nothing built for you.

Fishing · 04

Fishing Porcupine

Nine species, a limit that pays you to take kokanee, and eighteen thousand lake trout nobody has published catching.

Opens a live Google map. Pick a species, get the rule, the named spots and what people throw at it.

Kokanee salmon

The whole limit is built around it

Wild, and never stocked

Rainbow trout

Eleven to twelve inches, by truck

Catchables every May

Brown trout

What the locals chase at ice off

In the reports, not the list

Cutthroat trout

Present, and not managed for

Named in the rule itself

Splake

Brook trout crossed with lake trout

Fingerlings most summers

Lake trout

The biggest gap on this page

18,696 in, no catch out

Tiger trout

One delivery, five years ago

Stocked once, in 2021

Utah chub

What the big browns are eating

The agency calls it bait

Utah sucker

Forage, and legal cut bait

Not the June sucker

Drawings are illustrations of the named species, not photographs of fish caught here. Presence comes from the wildlife agency's own record for this water and from its own fishing reports . Where to fish and what to throw come from angler sources, marked with letters instead of numbers.

The guidebook entry for Porcupine Reservoir is four bullets :

Porcupine Reservoir, Cache County 2026 GUIDEBOOK

"Limit 12 trout and kokanee salmon, only 4 may be rainbow, cutthroat or brown trout (a combined total). To take 12 fish, you must possess at least 8 kokanee."
"See East Fork Little Bear River."
"Operating a boat above wakeless speed is prohibited."
"An angler may use up to six lines when fishing through the ice. If the angler is using more than two lines, the angler's name must be attached to each line, pole or tip-up, and the angler may check only their lines."

Read the first bullet again. The statewide trout limit is four. Here it is twelve, but only if at least eight of them are kokanee, and no more than four can be rainbow, cutthroat or brown . It is a limit built to move kokanee out of a water that grows too many of them.

The kokanee closure, in two parts DATES

Statewide, on the fish: "Anglers may not possess kokanee salmon at any waterbody statewide from Sept. 10 through Nov. 30 to protect kokanee during the spawning season."

Here, on the stream: the East Fork Little Bear River and its tributaries, from the reservoir up to the headwaters, are "CLOSED Aug. 15 through 6 a.m. on the last Saturday of September."

The stream shuts 26 days before the possession ban starts. That gap is the actual protection: the fish staging to run are off limits in the river while the reservoir is still open.

Two things you can do here and almost nowhere else RARE

Spearfishing. Porcupine is one of eight named reservoirs and lakes in Utah open to underwater spearfishing for game fish year round, alongside a cluster of Uinta high lakes . The guidebook is clear that the closures still bind: "Remember: All possession limits and seasonal closures apply, regardless of the fishing technique you use."

Multiple lines through the ice. Utah allows this at exactly four waters: Flaming Gorge, Causey, Pelican Lake and Porcupine . Up to six lines here, with your name on each.

There is no 15 to 22 inch slot limit at Porcupine A CLAIM WORTH KILLING

The wildlife agency's own July 2024 forecast for this reservoir ended with a line telling anglers all trout between 15 and 22 inches must be released , and commercial fishing sites have republished that line ever since. No such rule appears in the guidebook entry for Porcupine, in 2026 or any year we could check . The guidebook is the law. Fish the four bullets above.

Year	What went in
2026	7,564 lake trout, 7,459 rainbow, 1,763 splake
2025	3,753 lake trout, about 7,500 rainbow, 1,764 splake
2024	7,379 lake trout, about 6,016 rainbow
2023	2,560 rainbow, 505 splake
2022	2,586 rainbow
2021	2,501 rainbow, 848 splake, 3,000 tiger trout
Kokanee, any year	None

Rainbows go in as catchable fish of about eleven to twelve inches each May. Splake and lake trout go in as fingerlings of two to four inches in summer .

Eighteen thousand lake trout, and no one has written down catching one A REAL GAP

Since 2024 the wildlife agency has put 18,696 lake trout into this 190 acre reservoir . Its own species record rates them only Possible . No agency fishing report mentions catching one. No angler source we could find describes fishing for them here.

That is the largest unexplained gap on this page. Either the fishery has not turned over yet, or nobody is reporting it. This page is not going to invent a technique for a fish nobody has published catching.

Tiger trout were stocked once, 3,000 fish in November 2021, and have not been stocked since nor named in any agency report . They are on the species grid labelled for exactly that.

Recreation · 05

What to watch for

A private fence, spawning fish people keep touching, thin ice at the inlet, and nothing built for you.

The private boundary is 67 metres from the inlet DO NOT WALK UP

"Do not trespass on Cinnamon Creek Campground's land, which is located just upstream, and is marked with a 'no trespassing' sign and locked gate."

Cache County's parcel layer and OpenStreetMap put that western boundary in the same place to within four metres , and its nearest mapped point is 67 m from where the river enters the reservoir . The public walking is short. The map in the Recreation section has a pin on the campground so you can see the line before you go.

Do not touch the spawning fish THREE MISTAKES

"Visitors should also not disturb the spawning fish by wading into the water, allowing their dogs to chase the fish or by trying to pick the fish up."

And you may not keep a kokanee anywhere in Utah between 10 September and 30 November .

No ramp, no toilets, very little parking COME PREPARED

Porcupine is not in Utah's statewide boat ramp inventory , there is no state park or Forest Service site, and the wildlife agency describes parking as "very limited" . The pavement ends 659 m before the dam .

Weak ice at the inlet WINTER

Moving water thins ice from underneath. A long standing local account of ice fishing here warns specifically to be careful of weak ice near the inlet , which is exactly where the river enters and exactly where people want to fish.

Mussels, and what the rule actually is AIS

Porcupine is not listed as mussel infested. The guidebook: "Quagga mussels are present at Lake Powell and at many waterbodies outside the state." Porcupine appears nowhere on the infested list .

The rules still bind. Motorised boats must complete the annual mussel aware boater course and pay the yearly enrolment fee. Non motorised craft are exempt from the fee but "you are still required to complete the Utah Mussel-aware Boater course and self-certify that you've effectively cleaned, drained (if applicable) and dried your vessel before launching in a Utah waterbody." That covers a float tube or a kayak, which is most of what floats here.

A private irrigation pond that grows a wild salmon run, with a public walk of about sixty seven metres.

Fathom Restoration is a Utah 501(c)(3) that runs volunteer dive cleanups and is built to pull what does not belong out of Utah water, statewide.

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Every figure on this page is quoted from the source named beside it.